A technique to process a substrate by forming a fine pattern on the substrate and performing etching following the pattern is widely used in the field of semiconductor production.
With development of lithography techniques, patterns are refined, a KrF excimer laser or an ArF excimer laser is used, and an exposure technique using an electron beam or EUV (extreme ultraviolet) is under examination.
As one of pattern formation techniques, a pattern reversal method is employed. Specifically, resist patterns are first formed on a semiconductor substrate, and the resist patterns are coated with a silicon-based coating liquid. Thus, the silicon-based coating liquid is filled between the resist patterns, and then the resultant is baked to form a coating film. Thereafter, an upper portion of the thus formed silicon-containing coating film is etched back by etching with a fluorine-based gas to expose a top portion of the resist pattern, subsequently the gas is changed to an oxygen-based etching gas to remove the resist pattern, and thus, a silicon-based pattern derived from the silicon-based coating film remains instead of the eliminated resist pattern, and the pattern is thus reversed.
When the silicon-based film with the reverse pattern thus formed is used as an etching mask to etch a lower layer or the substrate, the reverse pattern is transferred, and the pattern is formed on the substrate.
As a pattern forming method utilizing such a reverse pattern, there is an invention utilizing a material using a polysiloxane, which is obtained by co-hydrolysis of a silane having a hydrogen atom, a fluorine atom, a straight chain or branched chain alkyl group having a carbon atom number of 1 to 5, a cyano group, a cyanoalkyl group, an alkylcarbonyloxy group, an alkenyl group or an aryl group, and a tetraethoxysilane, and an ether-based solvent (see Patent Document 1).
Besides, there is an invention utilizing a material using a hydrogen siloxane (see Patent Document 2).